@pointW: 12px;
@all: 100%;

#box {
    width: 100px;
    height: 100px;
    position: fixed;
    top: 20vh;
    left: 50vh;
    border: 3px dashed #7a7a7a;
    user-select: none;
    cursor: move;
    .point {
        width: @pointW;
        height: @pointW;
        background-color: aquamarine;
        position: absolute;

        &.lt {
            top: calc(0px - @pointW / 2);
            left: calc(0px - @pointW / 2);
            cursor: nwse-resize;
        }

        &.rt {
            top: calc(0px - @pointW / 2);
            left: calc(@all - @pointW / 2);
            cursor: nesw-resize;
        }

        &.lb {
            top: calc(@all - @pointW / 2);
            left: calc(0px - @pointW / 2);
            cursor: nesw-resize;
        }

        &.rb {
            top: calc(@all - @pointW / 2);
            left: calc(@all - @pointW / 2);
            cursor: nwse-resize;
        }

    }

}